As Global Navigation Satellite System (“GNSS”) receivers become more common, users expect improved performance in increasingly difficult scenarios. GNSS receivers may process signals from one or more satellites from one or more different satellite systems. Currently existing satellite systems include the global positioning system (GPS), and the Russian global navigation satellite system (GLONASS). Systems expected to become operational in the near future include Galileo, quasi-zenith satellite system (QZSS), and Beidou. For many years, inertial navigation systems have been used in high-cost applications such as aircraft to aid GNSS receivers in difficult environments. The recent trend is to try to integrate a GNSS receiver with low-cost inertial sensors to improve performance when many or all satellite signals are severely attenuated or otherwise unavailable. The high-cost and low-cost applications for these inertial sensors are very different because of the quality and kinds of sensors that are available.